Monolateral orthopedic device with external fixing for immobilizing a fractured bone

ABSTRACT

The invention applies to the field of medicine, particularly to bone surgery. The invention relates to a monolateral orthopedic external fixation device for immobilizing a fractured bone having a rigid support, at least two pins screwed into the bone and joined to the rigid support by a connecting mechanism comprising a pin-holding device composed of two identical parts forming a clamp whose two opposing faces have depressions. These depressions are able to receive and hold pins with diameters from 3 to 6 mm.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The technical area of the present invention is that of externalorthopedic devices designed to immobilize fractured limbs and reducefractures. These types of devices are used for osteosynthesis with anexternal fixation device.

Treatment of fractures that are open, dirty, have large openings, areold, or caused by projectiles with high kinetic energies requireexternal fixation. The fixation of a fracture, particularly an openfracture, must be stable, because compression, traction, twisting, andflexing stresses at the site of the fracture are transmitted to theexternal fixation device through the bone-pin connection. Rigidity ofthe fixation device is hence of the utmost importance in consolidatingthe bone fragments of a fracture. There are numerous external fixationdevices of different types—unilateral, frame, or circular—on the market.

The majority of operations with fixation devices performed on anemergency basis, particularly by field surgery under wartime or disasterconditions, usually have to be repeated because of reduction defects.Perfect initial surgery is rare.

There are only two options for the subsequent procedure:

remove the pins, re-perform the reduction, and reinsert the pins througha new connecting bar, thereby losing the value of the initial fixation;

leave the pins in place, and reduce by changing the assembly with twoshort bars (upper and lower) joined by a connecting means, whereby theassembly loses its initial rigidity.

2. Description of Related Art

External fixation devices composed of rigid tubes or equivalent means inwhich the pins engage and are held by screws are described for examplein patents FR 2,442,044, FR 2,551,650, and FR 2,553,994.

In particular, Patent 2,457,656 describes a unilateral type fixationdevice for reducing a fracture comprising a main tube supporting twotube segments joined to the first with spherical mounts. Collars allowthe two segments to slide relative to the main tube, and each tube has,in two mutually perpendicular planes, diametrically opposite, regularlyspaced, threaded holes to receive the pins and the locking screws.

These fixation devices, worn by ambulant patients, have numerousdrawbacks.

For instance, insertion on an emergency basis requires reduction andprovisional containment of the bone site, or at least correct alignmentof the limb if bone substance has been lost, before the pins areinserted. This constraint is the reason for many imperfect initialinsertions.

In addition, the spacing of the pins is strictly defined by the holes inthe tubes wherein the pins are located in a single plane and parallel toeach other. This prevents flexibility in orienting or spacing the pinsimplanted in the bone.

Further, an apparatus having a large number of component parts, eachhaving different diameters, develops to include a main tube, a tubesegment, a spherical mount, a collar, and a pin. The large number ofparts makes assembly difficult and is time-consuming when the surgeon isunaccustomed to their use.

Moreover, the various basic parts are not radiotransparent and are heavybecause they are made of metal. The latter point is a drawback not onlyfor the patient but also for field surgical teams carrying instrumentkits.

U.S. Pat. No. 4,483,334 describes an external fixation device forfractures having pins screwed into the bone on either side of thefracture, a pair of rods connected to these pins on either side of thefracture, and a bridge connecting the rods with each other. Theconnecting mechanisms connecting each pin to the rods consist of aone-piece U-shaped assembly clamped to the pins, and a collar that isadapted to the diameter of the rods. The pins, rod, pin assemblies, andcollars are held together by a single screw ensuring holding in alldirections.

German Utility Model DE 91 03 480 describes a device for immobilizing afinger or a hand in the event of a fracture consisting of spikes screwedon either side of the fracture that are held together by a connectingrod. The connecting mechanism between the spikes and the connecting rodis comprised of a U-shaped collar, a socket, a screw provided with ahole for the spike to pass through, and a nut. When the nut istightened, the spike is locked.

These two devices enable only one pin to be fixed by a connectingmechanism.

German Patent DE 295 12 917 describes an orthopedic device having a pinassembly for simultaneously holding at least two pins in parallel.

This assembly is composed of two identical parts forming a clamp. Theclamp has depressions on two opposing faces for gripping and holding thepins.

This assembly has the drawback of holding only one pin diameter. Inother words there is one type of assembly for each pin diameter. Thus,assemblies of different configurations must be available in order toachieve the immobilization desired.

Other orthopedic options are available that are lighter than theforegoing, and are made of radiotransparent and non-magnetic materials.An example of such is the fixation device described in French Patent FR2,688,685. This device has a solid, rigid rod having transverse orificesfor passage of pins screwed into the bone. These pins are fastened tothe rod by fixation inserts or tightening collars. However, the spacingof the orifices, and hence the spacing of the pins, is strictly definedand invariable.

SUMMARY OF THE INVENTION

One goal of the present invention is to provide an external orthopedicfixation device compatible with existing fixation devices, particularlythose used by the member countries of the North Atlantic TreatyOrganization (NATO), for precise reduction of fractures by preciseadjustments with several degrees of freedom.

Another goal of the present invention is to provide an orthopedic devicethat simplifies the installation of material by a non-specialistsurgeon, thereby offering the opportunity to correct axial defectswithout modifying the pins in place, or requiring additional epiphysealholding devices.

The further goal of the present invention is to provide an externalfixation device having good rigidity and simultaneously:

simplifying the repositioning of axial defects without modifying thepins in place;

providing compatibility with the pins of employed with various fixationdevices already in use, such as those employed in NATO countries;

enabling the use of the device by a non-specialist because the number ofcomponent parts is very small;

causing the reduction of fractures with the fixation device in place;

allowing muscle flaps to be created to cover the limbs involved by usinga single-plane or at least unilateral assembly;

exploring an extremely simple design of the epiphyseal holding devices;

using self-drilling and self-tapping pins of different diameters foradaptation the various types of surgery;

more easily monitoring bone consolidation by x-ray or magnetic resonanceimaging due to total radiotransparency of the device;

adding comfort to the patient because the implants are light.

For this purpose, the monolateral orthopedic device with external fixingfor immobilizing a fractured bone has, in known fashion, a rigid supportdisposed parallel to the bone, at least two pins screwed into the boneand joined to the rigid support by a connecting mechanism comprising apin-holding device composed of two identical parts forming a clamp whosetwo opposite faces have depressions. This device is characterized inthat the depressions are able to receive and hold pins with diametersfrom 3 to 6 mm.

Preferably, the depressions of the device have different directions,i.e., the depressions in one of the directions enable pins 3 or 4 mm indiameter and parallel with each other to be held, and the depressions inthe other direction, perpendicular to the previous direction, enablepins 5 or 6 mm in diameter and parallel with each other to be held.

Preferably, the connecting mechanism comprises a collar that can slidearound the support and a single removable screw providingomnidirectional locking of each connecting mechanism and each pinrelative to the support and its corresponding pin-holding device.

The pin-holding device can have a foolproofing mechanism, whereby thetwo identical clamp-forming parts each have a peg and a tongueaccommodated in an orifice and a notch respectively of the otheridentical part. This mechanism makes it possible to guide one of the twoparts relative to the other without hesitation.

Preferably, the device has means of assembling the pin-holding devicesto the collars. These means can be crenellated surfaces made in eachface to contact with the pin-holding devices and with each collar. Thisensures precise indexing, cohesion of the parts with each other, andfull immobilization of the pins relative to the rigid support.

Preferably, the collars, made of a flexible material, are clipped ontothe rigid support and the transverse support. They may have a spacer tomaintain a constant distance between the two ends of the collar andlimit the torque of the screw.

Preferably, the rigid support is comprised of a cylindrical tube made ofcarbon.

Preferably, the entire device, with the exception of the pins, is madeof a radiotransparent, non-magnetic material.

According to one embodiment, the device can have a transverse supportjoined to a rigid support by a collar to hold an epiphysis of thefractured bone using at least one pin screwed into the epiphysis and aconnecting mechanism mounted on the transverse support.

The various types of parts in the device can have different colors tofacilitate their identification when the device is mounted on thepatient.

This device has the advantage of having a very small number of parts.The minimizing of parts saves a great deal of time and facilitatesassembly of the device, both of which are essential in emergency surgeryby an inexperienced surgeon.

Another advantage is that the support/collar and collar/pin-holdingdevice connections allow the pins to move in all directions so that thedevice can be adapted when correcting alignment defects withoutmodifying pins already in place.

Because the material is a light weight carbeon-type synthetic material,the consolidation x-rays are easy to read and the device is easy for thesurgeon or patient to carry.

Another advantage is that the two types of pin-holding devices are fullycompatible with the various pins already used this type of operation.

Other characteristics and advantages of the invention will emerge fromthe detailed nonlimiting description provided below.

The description below refers to the attached drawings that represent,without being limiting in nature, one embodiment of an orthopedic devicewith external fixing according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an external fixation device in itsutilization condition, for example for immobilizing a fracture in a longbone of the femur type.

FIG. 2 is a view of the device according to FIG. 1, showing the mountingof a epiphyseal holding device.

FIG. 3 is a partial perspective view of the mounting of the pin-joiningmeans on a rigid support of the device, with a one-piece pin-holdingdevice.

FIGS. 3A and 3B show the arrangement in FIG. 3 in cross section.

FIG. 4 shows a one-piece pin-holding device in elevation.

FIG. 5 is an elevation view of a clamp-shaped pin-holding deviceaccording to the invention, showing its two identical parts dissociatedwith their outer and inner faces.

FIG. 5A is a plan view of the internal face of one of the identicalparts of FIG. 5.

FIG. 5B is a cross-sectional view along line AA in FIG. 5B.

FIG. 6 is a view according to FIG. 3 of the mounting of two pins on arigid support with the aid of a clamp-shaped pin-holding device.

FIGS. 6A and 6B show the mounting arrangement of FIG. 6 in crosssection.

FIG. 7 shows two elevations of a collar according to the invention.

FIG. 8 is a partial elevation view of the epiphyseal mountingarrangement shown in FIG. 2.

FIG. 8A is the mounting arrangement of FIG. 8 in a top view.

FIG. 8B is a partial cross-sectional view along line AA in FIG. 8A.

The attached figures show a monolateral orthopedic device with externalfixing used for temporary immobilization of a fractured bone 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As an example, FIGS. 1 and 2 show a device according to the inventiondisposed in parallel on a fractured femur 2 of a thigh 1 of an injuredpatient. The device is placed along and outside thigh 1. Femur 2 isshown after reduction of the fracture.

The device has at least two pins 3 screwed into bone 2 on either side ofthe fracture and joined to a rigid support 4 by a connecting mechanism.

Pins 3 of a known type, made of a stainless-type metal, are preferablyprovided with a self-tapping end and can be 3 to 6 mm in diameter.

Rigid support 4 is comprised of a smooth cylindrical tube made in knownfashion by winding carbon fibers.

The connecting mechanism is a combination of a pin-holding device 6 or 7with a collar 5, using a single fixation means screw 8 a.

Collars 5, made of a flexible synthetic material, are clipped onto rigidsupport 4 and can slide around and along it. These collars 5, adapted tothe diameter of the rigid support and U-shaped, are perforated at eachend (FIG. 7). A crenellated ring 5 a is formed in the outer part of oneof the ends and a removable spacer 5 b, made of a hollow cylindricaltube, is disposed between the two ends of the collars to keep them at aconstant distance from each other. The outer part of the orificeprovided in this crenellated ring end has a circular opening 5 c tofacilitate the relative positioning of each collar relative topin-holding devices 6 or 7. An insert 8 b is lodged in the orifice ofthe other end of the collar and sunk in the thickness of this end. Thisinsert is provided with a threaded orifice.

The bodies of both types of pin-holding devices, 6 and 7, are piercedtransversely.

Fixation means screw 8 a is a threaded screw of known type long enoughto pass through the transverse opening of the pin-holding device, spacer5 b, and the ends of the corresponding collar 5. The fixation means endof the screw 8 a engages the threaded orifice of insert 8 b to ensurelocking of the connecting mechanism and the corresponding pins 3 in alldirections, once the screw has been tightened.

The length of spacer 5 b is adjusted to limit the tightening torque offixation means screw 8 a, while completely immobilizing collar 5relative to rigid support 4 once screw 8 a has been locked.

The device has two different types of pin-holding devices 6 and 7.

Pin-holder 6, FIG. 4, is made of a one-piece U-shaped part comprisingtwo symmetrical rectangular sides connected to each other by a curved,elastic element so that the end of at least one pin 3 can be clippedbetween the two rectangular elements. The sides of pin-holder 6 have aninternal bevel to facilitate insertion of the ends of pins 3.

Clamp-shaped pin-holder 7FIGS. 5 to 5B, has two rectangular dissolvableparts having a peg 7 d projecting on their inner faces, an eccentrictransverse orifice 7 f, a notch 7 g in one of the sides, and a flexibletongue 7 e attached to the opposite side.

When the two dissolvable parts are assembled, peg 7 d and tongue 7 e ofone of the parts are accommodated in orifice 7 f and notch 7 grespectively of the other part to form a clamp in which the ends of thetwo pins 3 are placed. If necessary, this pin-holding device 7 issuitable for receiving the end of a single pin 3.

The outer faces of the two pin-holding device types 6 and 7 have acrenellated ring 6 a and 7 a identical to the ring 5 a of collars 5.Crenellated ring 5 a of the collar is placed in contact with crenellatedring 6 a or 7 a of the pin-holding device 6 or 7 used, to ensure preciseindexing and optimize their cohesion and immobilization relative torigid support 4.

Depressions 6 b and 7 b are provided in the thickness of the inner facesof the two pin-holders 6, 7 and each receives the end of a pin 3. Thesedepressions 6 b, 7 b are in the shape of a recess with a triangularsection, FIGS. 4, 5B, over the entire length or width of pin-holdingdevices 6 and 7. The particular shapes of these depressions prevent anypossibility of the cylindrical end of the pin rotating inside device 6or 7.

When bone 2 is fractured at epiphysis 2 a, FIG. 2, pins 3 have to beplaced in this epiphysis to ensure correct immobilization of thefractured bone.

For this purpose, the device has a transverse support 9 joined to rigidsupport 4 by a collar 5 similar to that described above.

This transverse support 9 is made of a small cylindrical tube made ofcarbon of the same type as rigid support 4. It is pierced along itslengthwise axis for insertion through one of its ends of a threadedscrew 9 a, FIG. 8B, or any other equivalent means, and screwed to insert8 b of a collar 5 to fasten it to rigid support 4 once screw 9 a hasbeen tightened.

This screw is similar to the screw 8 a described above, but is longer sothat it can adapt to the length of transverse support 9 and the spacingof the ends of collar 5. A crenellated ring 9 b positioned oncrenellated ring 5 a of collar 5 is provided on the section of the otherend of transverse support 9 to improve the fixation of this support tothe collar while preventing any rotational movement of transversesupport 9. One or more connecting mechanisms are mounted on this support9, which has the same diameter as rigid support 4, as described above.

Except for pins 3, the entire device is made of a radiotransparent,non-magnetic material of the carbon type. This highly rigid material isalso highly resistant to a repeated temperature of 140° and to theproducts used for sterilizing the device as a whole. To facilitateapplication of the device to the patient, the various types of partsused are in different colors.

The monolateral orthopedic device with external fixing operates asfollows.

Once the fracture in bone 2 has been reduced and at least two pins 3have been inserted on either side of the fracture, the surgeon mounts aconnecting mechanism on the end of each pin. The connecting mechanismcomprises at least a collar 5, pin holder 6, 7, pins 3, a fixation meansscrew 8 a, insert 8 b and rigid support 4.

A pin 3 end is clipped to a one-piece pin-holder device 6 and positionedin depression 6 b. A collar 5 is placed on rigid support 4 and a spacer5 b is disposed between the ends of collar 5. Collar 5 and pin-holderdevice 6 are joined by placing crenellated rings 5 a and 6 a in contact.Thus, the orifices 6 c, 5 c of the pin-holder and collar respectively,and the spacer 5 b are aligned for subsequent introduction of fixationmeans screw 8 a, and the mechanism is locked by tightening it with awrench until spacer 5 b abuts the ends of the collar 5.

To join two neighboring pins 3with rigid support 4, one side of aclamp-shaped pin-holder 7 is placed on the ends of the two pins 3, thenthe other side of pin-holder 7 is placed on the previous side by joiningthe peg 7 d and tongue 7 e of one side with orifice 7 f and notch 7 g ofthe other, respectively. At the same time, the ends of pins 3 arepositioned in depressions 7 b.

Assembly of this pin-holding device 7 with a collar 5 and rigid support4 remains identical to the assembly described above.

Before fixation means screw 8 a is tightened all the way, the angulararrangement of each connecting mechanism relative to pins 3 and rigidsupport 4 is precisely adjusted by modifying the relative positions ofcrenellated rings 6 a, 7 a, and 5 a and moving collars 5 on rigidsupport 4 rotationally and translationally.

For the epiphyseal mounting arrangement, a transverse support 9 isjoined to rigid support 4 by a collar 5 provided with a spacer 5 b, thecollar having previously been placed on the rigid support 4.

The crenellated ring 9 b formed on the section of the end of transversesupport 9 is positioned on ring 5 a of the collar, then screw 9 a istightened until spacer 5 b abuts the ends of the collar 5.

The connecting mechanisms are mounted on transverse support 9 in thesame way as described for rigid support 4.

Preferably, screw 9 a is held inside transverse support 9.

This device has a very small number of parts and is extremely simple tomount, making it fully suitable for emergency operations conducted underparticularly arduous conditions.

The orthopedic device with external fixing for immobilizing a fracturedbone has just been described, solely as a nonlimiting example. Ofcourse, a number of modifications to the above example can be made byone skilled in the art without departing from the scope of protectiondefined by the attached claims.

What is claimed is:
 1. A monolateral device with external fixing forimmobilizing a fractured bone comprising: a rigid support; at least twopins screwable into the bone and joined to the rigid support by aconnecting mechanism comprising a pin-holding device composed of twoparts forming a clamp whose two opposing faces have depressionsextending different directions, the depressions in one of the directionsenabling pins 3 or 4 mm in diameter and parallel with each other to beheld, and the depressions in the other direction, perpendicular to theprevious direction, enabling pins 5 or 6 mm in diameter and parallelwith each other to be held; a collar that can releasably translate androtate about the rigid support; and a single removable screw, whereinthe collar and the pin-holding device have crenellated surfaces made tocontact one another to ensure precise indexing of the pin-holding devicerelative to the collar about a rotational axis of the collar, cohesionof the elements with each other, and full immobilization of the pinsrelative to the rigid support, and the single removable screw providesomnidirectional locking of each connecting mechanism and each pinrelative to the rigid support and its corresponding pin-holding device.2. The device according to claim 1, wherein the collar has a spacer tomaintain a constant distance between two ends of the collar and limitthe torque of the single removable screw.
 3. The device according toclaim 1, further comprising a second connecting mechanism include asecond pin-holding device comprising a one-piece, U-shaped part havingan internal bevel to receive one of the pins, a second collar that canslide around the rigid support, and a second single removable screw,wherein the second collar and the second pin-holding device havecrenellated surfaces made to contact one another to ensure preciseindexing of the second pin-holding device relative to the second collarabout a rotational axis of the second collar, cohesion of the elementswith each other, and full immobilization of the pins relative to therigid support, and the second single removable screw providesomnidirectional locking of the second connecting mechanism and each pinrelative to the rigid support and its corresponding pin-holding device.4. The device according to claim 1, wherein the pin-holding device has afoolproofing mechanism guiding the positioning of one clamp-forming partrelative to the other.
 5. The device according to claim 4, wherein thefoolproofing mechanism includes, on each of its clamp-forming parts, apeg and a tongue accommodated in an orifice and a notch respectivelymated with the opposing side of the clamp.
 6. The device according toclaim 4, wherein the collar has a spacer to maintain a constant distancebetween two ends of the collar and limit the torque of the removablescrew.
 7. The device according to claim 1, wherein the rigid support iscomprised of a cylindrical tube made of carbon.
 8. The device accordingto claim 7, wherein the entire device, with the exception of the pins,is made of a radiotransparent, nonmagnetic, material.
 9. The deviceaccording to claim 8, further comprising a transverse support joined tothe rigid support by another collar to hold an epiphysis of fracturedbone using at least one pin screwed into the epiphysis and a connectingmechanism mounted on the transverse support.
 10. A monolateral devicewith external fixing for immobilizing a fractured bone comprising: arigid support; at least two pins screwable into the bone and joined tothe rigid support by a connecting mechanism comprising a pin-holdingdevice composed of two parts forming a clamp whose two opposing faceshave depressions extending in two intersecting planes, wherein thedepressions in one plane are sized to enable pins 3-4 mm in diameter tobe held in parallel with each other and the depressions in the secondplane are sized to enable pins 5-6 mm in diameter to be held in parallelwith each other; a collar for each pin-holding device that canreleasably translate and rotate about the rigid support; and a removablescrew for each pin-holding device, wherein the collar and thepin-holding device have crenellated surfaces made to contact one anotherto ensure precise indexing of the pin-holding device relative to thecollar about a rotational axis of the collar, cohesion of the elementswith each other, and full immobilization of the pins relative to therigid support, and the removable screw provides omnidirectional lockingof each connecting mechanism and each pin relative to the rigid supportand its corresponding pin-holding device.